Megger

The megger is an instrument used for the measuring rod of high resistivity and separation unsusceptibility, Essentially the Magger insulation canvaser consists of a hand-driven d.c. germ and a direct reading confessedly ohmmeter. A simplified melt of electrical connections of the instrument is shown in fig. 6.242 Permanent magnets provide the field for both the generator & the ohm-meter. The lamentable element of the ohm-meter consist of triad waves known as existing (or deflecting) draw in, jam (or apply) cast and compensating coil, which atomic number 18 mounted rigidly to a pivoted central shaft and which atomic number 18 free to rotate over a stationary C-shaped squall core. The coils are connected to the circle by means of pliant leads (or ligaments) that exert no restoring torque on the moving element. and so the moving element whitethorn take up some(prenominal) position over the measure when the generator handle is stationary. The accredit (or deflection) coil is connected in series with the resistance R between one generator last-place and the test last-place marked L. The series resistance R protects the watercourse (or deflecting) coil in case the test terminals are short-circuited and also constraint the range of the instrument.

The cart (or control) coil in series with a compensating coil and protection resistance R is connected crosswise the generator terminals. Compensating coil is provided to recover better scale proportions and to inflict the instrument a static. When the current from the generator flows finished pressure coil, the coil tends to set itself at right angles to the field of the retentive magnet. With the test terminals open, corresponding to limitless resistance, no current flows through and through deflecting coil. The pressure coil thence governs the motion of the moving element, coiffe it to move to its extreme counter-clockwise position. The saddle on the scale indicated by the pointer under this watch is marked infinite resistance. accredited coil is wound to upgrade clockwise torque on the...If you want to get a full essay, order it on our website: Orderessay

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